In the existing Long Term Evolution-Advanced (LTE-A) system, the Relay technology is introduced and mainly used for increasing the throughput of the cell edge, expanding network coverage, providing group mobility services, etc. A Relay Node (RN) is connected with a donor node in a wireless way, and connected to a core network through the donor node. A wireless link between the RN and the donor node is called a backhaul link, and a wireless link between the donor node and a UE served by the donor node and between the RN and a UE served by the RN is called an access link. In the LTE-A system, the donor node of the RN is a macro eNB (DeNB).
In a backhaul link from the RN to the macro eNB, single hop exists between the RN and the macro eNB, and there are only one macro eNB serving an RN at the same moment. A mode of pre-configuration or Operation Administration and Maintenance (OAM) entity configuration is adopted at the network side to determine a donor node for the RN. In the mode of pre-configuration, information of a cell to which the RN can be accessed is pre-configured by the operator before the RN starts up, and the information is stored in the RN. When the RN is started for cell search, the RN performs the cell selection in a pre-configured set of cells, and selects a cell with the best signal quality as a donor cell. In the mode of OAM configuration, the RN conducting as a user equipment accesses to a selected cell after starting up, and is configured with the information of the donor cell through OAM after being identified as the RN by the network side. After obtaining the information of the donor cell, the RN accesses to the selected donor cell and is provided with a backhaul service by the donor cell.
In future development of the mobile communication system, to better meet the demands of users and increase the capacity and throughput of the network, more access nodes (hereafter called small stations) with low power and small coverage will be introduced, i.e. Ultra-Dense Network (UDN) in the future. In the UDN, the network is flexible, for example, in a distributed network or hybrid network, the deployment of an Access Point (AP) is flexible, and usually plug-and-play, so pre-configuration by an operator cannot be realized; and the number of nodes in the UDN is large, and a list of donor cells which OAM is required to be configured with is very large, which will cause configuration and maintenance to be very difficult. Also, due to the large number of nodes, a single-hop backhaul path cannot support the backhaul requirements of multiple nodes in the UDN.
In conclusion, the method of providing the single-hop backhaul path through pre-configuration or OAM configuration cannot satisfy the backhaul requirements of small stations deployed flexibly in the UDN.